Fermentation processes are widely used for the purpose of producing pharmaceutical bio-molecules to be used as the active agent in pharmaceutical preparations as well as for a number of other types of bio-molecules e.g. enzymes, organic acids etc.
Fermentation processes for production of pharmaceutical bio-molecules by micro-organisms are very difficult to control. Due to this some processes may have a recovery of the bio-molecules produced of only 50% or even much lower. The problem is that it is very difficult to get a sensor system that can handle a dynamic complex fluid, which also is bubbling and foaming, and monitor the activity or bio-mass of the micro-organisms, e.g. growth of the bio-mass. A sensor system enabling both the characterisation of a complex fluid, in which gas bubbles and foam are produced, and the monitoring of the bio-mass growth is not yet available on the market.
On-line measurement of the biological activity/bio-mass of the micro-organisms in the process is desired in order to make it possible to instantly adjust the process based on such measurement.
It should be noted that, normally, the micro-organisms and the bio-molecules produced by the process are present as a dispersion in a fluid, normally a liquid.
The rheological properties of food products, such as dairy products, are very important as they determine quality aspects such as product stability, taste and mouth feel. These properties are defined by bio-molecules and/or emulsion droplets and/or crystalline particles and their content and quality. Different processes, for example denaturation of whey, homogenisation of milk, and crystallisation of detergents are used to obtain the desired properties.
Whey is a milk product obtained as a by-product during, for example, cheese production. The whey obtained during such production is dried, preferably spray dried, or concentrated by membrane technologies, and used in other food products. The surplus is sometimes used as fodder.
The original protein molecule or bio-molecule in diluted whey has a three dimensional structure with inter-chain bonding. The protein molecules are to some degree changed during the denaturation process due to pH and temperature changes. Thereby, the protein is denatured to a varying degree. Accordingly, the protein takes part in a denaturation process.
The denaturation alters the functional character of the whey. For example, the interaction with water and thus the solubility and viscosity when re-dispersed is altered by the denaturation. Thus, both the rheological properties and the aggregate size distribution is altered. In order to obtain a high quality whey product and, simultaneously, to reduce total costs for the production thereof, it is important to control the degree of denaturation continually or continuously during the process.
During homogenisation of an emulsion, for example milk, the fat droplets are subjected to shear forces and disrupted to various degrees. A smaller droplet size distribution is obtained and thus the stability of the emulsion is increased. Also the taste and mouth feel of the product is altered. It is important to control the droplet size distribution and viscosity to obtain desired product quality.
Crystallisation processes are applied in manufacturing of many different types of chemicals such as pharmaceuticals, detergents, enzymes, fertilisers, insecticides, herbicides as well as inorganic salts. Of special interest is also crystallisation based separation systems. The most crucial parameters to monitor for control of these processes are particle-size distribution and rheological properties. If these can be controlled by a reliable monitoring system higher product quality, e.g. purity and narrower particle size distribution, as well as better down stream processing conditions, e.g. filtration, can be obtained.